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IteratorDemo
`import java.util.*;class IteratorDemo{    public static void main(String arg[])    {        ArrayList<Integer> numbers = new ArrayList<Integer>();        numbers.add(10);        numbers.add(20);        numbers.add(30);        numbers.add(40);        numbers.add(50);        Iterator<Integer> itr = numbers.iterator();        while (itr.hasNext())         {            int number = itr.next();            System.out.print(number + " ");            if (number == 30)                itr.remove();        }        System.out.println("\n..................");        itr = numbers.iterator();//LINE A        while (itr.hasNext())         {            int number = itr.next();            System.out.print(number + " ");        }            }}`
OUTPUT

10 20 30 40 50
..................
10 20 40 50

DESCRIPTION

This example explains all the 3 methods of `iterator`. The first `while` loop displays all the elements of the list `num` and it comes out of the loop when the iterator has no next element. It also removes element 30 from the list `num`. The second `while` loop displays the elements after removing 30 from the list `num`.

THINGS TO TRY
• Try this program by removing `LINE A`. The output is as shown below.
10 20 30 40 50
..................

The condition in the second `while` loop will become `false`, since there is no next element. That is because in the previous `while` loop the end of the list is reached. If we call `hasNext` at the end. it will return `false`.
• Place the below shown code in the above program and check the output.
`ArrayList<Integer> numbers = new ArrayList<Integer>();numbers.add(10);Iterator<Integer> itr = numbers.iterator();while (itr.hasNext()) {    int number = itr.next();    itr.remove();    System.out.print(number + " ");}System.out.println(numbers.size());`
Remember `hasNext` becomes `true` if the list has atleast one element. So the output of the above code will be 10.